CD274 and esophageal squamous cell carcinoma: Based on the advanced ESCC of the KEYNOTE-590 clinical trial data, a Markov model was performed to simulate the clinical course and evaluate the patient's total lifetime, total costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratio (ICER) for pembrolizumab plus chemotherapy (cisplatin and 5-fluorouracil) vs. chemotherapy alone in first-line treatment of ESCC and PD-L1 CPS of 10 or more.